In situ determination of radon in surface water bodies by means of a hydrophobic membrane tubing

Schubert, Michael; Schmidt, Axel; Paschke, Albrecht; López, Abraham Sánchez; Balcázar, M.

doi:10.1016/j.radmeas.2007.12.017

Cited by 40 publications

(21 citation statements)

References 22 publications

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“…An additional method used to assess the radon activity in groundwater utilized a porous membrane tubing (Accurel tubing made by Membrana) to collect radon from the water via diffusion across the membrane (Freyer et al 2003;Schubert et al 2008). A closed air loop was created between the RAD7 and the membrane tubing to allow for constant recirculation of the airstream until it reached activity equilibrium with the radon in the water.…”

Section: Methodsmentioning

confidence: 99%

Quantification of point‐source groundwater discharges to the ocean from the shoreline of the Big Island, Hawaii

Peterson

Burnett

Glenn

et al. 2009

Limnology & Oceanography

109

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Aerial thermal infrared imaging has revealed that submarine groundwater discharge (SGD) along the western coast of the Big Island of Hawaii is often focused as point-source discharges that create buoyant groundwater plumes that mix into the coastal ocean. We quantified the SGD fluxes associated with several plumes using natural geochemical tracers. Offshore transects of 222 Rn and 224 Ra show elevated activities and corresponding low salinities in the nearshore waters within the plumes, indicating that these naturally occurring radionuclides can be useful tracers of groundwater inputs in this area. Using a series of simultaneous mass balance equations for water, salt, and radon, we determined the groundwater fluxes of six plumes near Kona, Hawaii. The average SGD fluxes ranged from 1100 m 3 d 21 to 12,000 m 3 d 21 of total (fresh + saline) SGD. The fresh (meteoric) groundwater equivalents for the same flows, modeled by adjusting the groundwater end member to reflect freshwater rather than brackish groundwater composition, ranged from 630 m 3 d 21 to 8600 m 3 d 21 . These fluxes are in general agreement with earlier results obtained by hydrological water budgets and physical oceanographic analyses of fresh SGD rates in this region.

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Section: Methodsmentioning

confidence: 99%

Quantification of point‐source groundwater discharges to the ocean from the shoreline of the Big Island, Hawaii

Peterson

Burnett

Glenn

et al. 2009

Limnology & Oceanography

109

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“…15 The film thickness on the air side can be assumed to be in the same range. 15 However, if air and water are separated by an air/radon-permeable but hydrophobic, i.e., water-repellent, membrane, as is the case for radon measurement after membrane extraction, 8,9 the film thickness on both sides of the interface is significantly different from the values valid for a fluid/fluid interface. In this case the film thickness on the air side equals the thickness of the applied membrane or is even larger if the membrane pores show a considerable tortuosity.…”

Section: ■ Theoretical Backgroundmentioning

confidence: 99%

Kinetics of the Water/Air Phase Transition of Radon and Its Implication on Detection of Radon-in-Water Concentrations: Practical Assessment of Different On-Site Radon Extraction Methods

Schubert

Paschke

Bednorz

et al. 2012

Environ. Sci. Technol.

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The on-site measurement of radon-in-water concentrations relies on extraction of radon from the water followed by its detection by means of a mobile radon-in-air monitor. Many applications of radon as a naturally occurring aquatic tracer require the collection of continuous radon concentration time series, thus necessitating the continuous extraction of radon either from a permanent water stream supplied by a water pump or directly from a water body or a groundwater monitoring well. Essentially, three different types of extraction units are available for this purpose: (i) a flow-through spray chamber, (ii) a flow-through membrane extraction module, and (iii) a submersible (usually coiled) membrane tube. In this paper we discuss the advantages and disadvantages of these three methodical approaches with particular focus on their individual response to instantaneously changing radon-in-water concentrations. After a concise introduction into theoretical aspects of water/air phase transition kinetics of radon, experimental results for the three types of extraction units are presented. Quantitative suggestions for optimizing the detection setup by increasing the water/air interface and by reducing the air volume circulating through the degassing unit and radon detector are made. It was shown that the flow-through spray chamber and flow-through membrane perform nearly similarly, whereas the submersible membrane tubing has a significantly larger delay in response to concentration changes. The flow-through spray chamber is most suitable in turbid waters and to applications where high flow rates of the water pump stream can be achieved (e.g., where the power supply is not constrained by field conditions). The flow-through membrane is most suited to radon extraction from clear water and in field conditions where the power supply to a water pump is limited, e.g., from batteries. Finally, the submersible membrane tube is most suitable if radon is to be extracted in situ without any water pumping, e.g., in groundwater wells with a low yield, or in long-term time series, in which short-term variations in the radon concentration are of no relevance.

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“…Outstanding examples are the localization and evaluation of non-aqueous phase liquid contamination in soils and aquifers (Schubert et al, 2001(Schubert et al, , 2007, the investigation of groundwater/surface water interaction processes (Burnett and Dulaiova, 2003;Schubert et al, 2008;Schmidt et al, 2009Schmidt et al, , 2010Schubert et al, 2010b), or the estimation of groundwater flow velocities (Cook et al, 1999;Hamada, 2000;Schubert et al, 2010a).…”

Section: Radon As Aqueous Tracer E General Remarksmentioning

confidence: 99%

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

Schubert¹,

Schmidt²,

Muller³

et al. 2011

Journal of Environmental Radioactivity

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In situ determination of radon in surface water bodies by means of a hydrophobic membrane tubing

Cited by 40 publications

References 22 publications

Quantification of point‐source groundwater discharges to the ocean from the shoreline of the Big Island, Hawaii

Quantification of point‐source groundwater discharges to the ocean from the shoreline of the Big Island, Hawaii

Kinetics of the Water/Air Phase Transition of Radon and Its Implication on Detection of Radon-in-Water Concentrations: Practical Assessment of Different On-Site Radon Extraction Methods

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

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